In general, abrasive articles such as bonded abrasives (e.g., grinding wheels and grinding stones), coated abrasives and three-dimensional low density nonwoven abrasives include a bond system which bonds the particles of abrasive grain to and/or within the abrasive article. The bond system for abrasive articles typically comprises glutinous or resinous adhesive material which may include additives such as inorganic fillers, grinding aids, surfactants, wetting agents, dyes and/or plasticizers. Examples of glutinous or resinous adhesive include hide glue, phenolic resins, urea-formaldehyde resins, melamine-formaldehyde resins, epoxy resins, acrylate resins, urethane resins, varnishes and combinations of two or more of these.
Bond systems for abrasive articles commonly include phenolic resin as the adhesive material. Phenolic resin provides the heat resistance, hardness, and strength required for abrasive-type applications. Abrasive articles containing coarse grade abrasive grain, which are generally used for high pressure, high stock removal applications, usually place the most severe burden on a bond system. The bond system must be able to hold the abrasive article together under these conditions which can include thermal shocks and extreme pressures at the grinding interface.
The resin is a critical component of the abrasive article. If the resin cannot withstand these severe and rigorous abrading conditions, it will no longer hold the abrasive article together and the article will fail. Failure under such conditions may create a serious safety hazard and can cause parts of the article and/or abrasive grain to be propelled from the article at high speed. The propelled material could injure the operator and/or others who may be nearby.
Furthermore, some organic resins may degrade when exposed to high temperature. This degradation reduces the bonding power and support of the bond system, resulting in loss or reduction in effectiveness at high temperatures. While there have been many suggestions of making modifications in the bond system in an attempt to overcome such problems, there still remains considerable room for improvement.
Certain references describe the addition of phthalocyanine, a highlv aromatic, thermally stable compound, to resinous materials, but not for the acknowledged purpose of improving the resistance to thermal degradation of the resin to improve the abrasive performance of an abrasive article. For example, NASA publication, Volume 10, Number 2, Item 108, published March/April, 1986, describes using a phthalocyanine precursor as a lubricant additive forming a metal phthalocyanine in situ to provide a protective and lubricating coating. Russian Pat. No. 812550, published Mar. 25, 1981, discloses the mixture of copper phthalocyanine and a rubber binder for an abrasive tool, e.g., grinding wheel. Additionally, U.S. Pat. No. 4,078,340, assigned to te assignee of the present application, discloses a nonwoven abrasive product made with a phenolic binder which contains a color pigmenting amount (less than 0.5% by weight) of phthalocyanine green. Achar et al, in an article entitled "Metal (II) 4,4', 4", 4'"-Phthalocyanine Tetramines as Curing Agents for Heat Reactive Epoxy Formulations", Journal of Polymer Science; Polymer Chemistry Edition, Vol. 21, 1505-1516 (1983), disclose using amino-substituted phthalocyanine as a curative for epoxy resin. Achar et al, in an article entitled "Mass Spectroscopy of Epoxylated Novolac Resin Cured with Phthalocyanine Tetraamines", Journal of Polymer Science: Polymer Chemistry Edition, Vol. 22, 1471-1479 (1984), disclose curing epoxylated novolac resin with metal (II) phthaloycanine tetraamines. Also, a recently published article by Itoh et al entitled "Functional Metallo-Macrocycle Derivatives and their Polymers 19. Synthesis of Water Soluble Metallophthalcyanine Derivatives and Formaldehyde Condensation with Methylolurea" Journal of Polymer Science: Part C: Polymer Letters, Vol. 25, 413-416 (1987) discloses the formaldehyde condensation of amido-substituted metallophthalocyanine with phenol or resole to produce novolac or resole phenol resin.
While the prior art discussed above discloses mixing phthalocyanine compounds with synthetic resins and reacting phthalocyanines with resins such as epoxy, it does not disclose prior to the present invention the reaction of phthalocyanine compounds with phenolic resin. Also, there is no disclosure prior to the present invention of more than a pigmenting amount of a phthalocyanine compound being mixed or reacted with a hard curable resin to provide a bond system for coated or three-dimensional, low density abrasive articles.